Magazine Extensions: How they work and why you need them

From time immemorial, shooters have been on a quest to increase the ammunition capacity of their firearms. The early days of percussion revolvers gradually progressed to modern magazine-fed firearms and while the need for appropriate shot placement and ammunition selection remains important, the reality is you can never have enough ammunition – especially for applications involving personal protection.

Unless you exclusively own revolvers or belt-fed weapons, magazines are a staple of any firearms collection. I’m somewhat embarrassed to admit how many magazines I have – it’s a lot. In my years of owning and using firearms both in and out of uniform, I’ve come to some hard realizations, including the fact that multiple magazines and more ammunition ARE NOT an answer for poor marksmanship and tactics. They are a supplement for the worst-case scenario. Lethal force encounters where shots are fired are relatively rare. However, if engaged in a gunfight, the odds are already not in your favor. Accordingly, Murphy’s Law suggests that if something can go wrong, it will. Pistols are convenient to carry and the ballistics of a pistol cartridge don’t always guarantee the mythical “one shot stop” in a defensive scenario. More ammo on your person is beneficial to counter the aforementioned problems. Some examples if increasing the amount of ammo carrier are: an additional magazine in the event your primary magazine malfunctions or fails (yes, I’ve experienced and seen this multiple times), multiple assailants, and potential active killer events.

The next question for many is, “How do I carry more ammunition?”

One option is to stack your belt and pockets with spare mags; an answer of profoundly uncomfortable and absurd proportions. Another option is to utilize a magazine with an extension. Magazine extensions are an excellent option for applications such as personal defense, competitive shooting, high-volume hunting (i.e. prairie dog, wild hog, etc.), and your average range day. Further, they’re relatively more affordable and reliable than the options of yesteryear.

The Basic Magazine Types

For simplicity’s sake, let’s isolate magazines into three categories: limited-capacity, standard-capacity, and high/increased-capacity magazines. A standard magazine is a magazine as it is offered by the manufacturer with the capacity it was originally produced to have. For example, a standard Glock 17 magazine is designed to accept 17 rounds of 9mm Luger ammunition. A limited-capacity variant of that magazine would only accept 10 rounds of the same ammo. Limited magazines really only exist to comply with local, state, or federal restrictions on firearms capacity.

From left to right: A limited capacity Glock 22 magazine, standard capacity Glock 17 magazine, Glock 17 magazine with plus 6 magazine extension, and extended 33-round Glock magazine.

The term “high-capacity magazine” is frequently misapplied or misused as are many other terms used in the firearm industry. Much like the misuse of “clip” versus “magazine,” high-capacity magazines are often confused with standard-capacity magazines. High-capacity magazines are best defined as magazines that have an increased capacity from what is standard production for a specific firearm. Returning to the Glock 17 example used above, Glock’s 33-round magazine or a 50-round MagPul drum magazine would be considered high-capacity mags. The classic 17-round magazine for the Glock 17 can also be modified with an extended floorplate (magazine extension) to increase its capacity. For instance, a Glock 17 magazine with a TTI +6 baseplate increases the factory standard-capacity magazine to 23 rounds. But classifying a standard-capacity 17-round magazine as a high-capacity magazine just because it holds more than 10 rounds is highly inaccurate and will likely yield an eye roll from experienced shooters.

Benefits of Magazine Extensions

Magazine extensions are a popular option for increasing the capacity of standard magazines to carry more ammunition. Most magazine extensions offer between two to six additional rounds from the original factory configuration. These extensions offer relatively compact enhancements to a factory magazine that serve numerous benefits to the user. Those benefits expand beyond the increased capacity of the firearm.

Extended magazines provide additional surface area for the user to grasp the magazine during a draw from a magazine pouch or pocket. One of my favorite forms of off-duty carry is a Glock 17 or 19 in the appendix position with a spare magazine in my front pants or shorts pocket. The spare magazine is oriented using a pocket magazine holster. With the magazine extension, it’s extremely easy to access the magazine from my pocket due to its extended length. When the mags with extensions are carried in a magazine carrier on my belt, it’s even easier to draw the magazine and insert it into the firearm.

A magazine outfitted with an extension also improves the user’s ability to remove the magazine from a firearm in the event it doesn’t drop free upon pressing the magazine release. The same holds true for malfunction clearance drills where the magazine must be removed (i.e. double-feed stoppage, magazine failure, etc). The extension hanging below the firearm’s grip makes magazine removal exceptionally easy in a rush.

Glock 34 with a plus 6 magazine inserted. The highlighted red area is where the normal flush-fitting magazine would sit. Extended magazines offer an increased surface area that helps with manipulating them for insertion or removal.

Magazine extensions have the obvious benefit of increasing a firearm’s capacity. Furthermore, most extensions do so with minimal increase to the overall size of the magazine. A Glock 17 magazine is approximately 5” long and holds 17 rounds. A plus six (adds six additional rounds to normal capacity) extension adds less than an inch to the magazine’s overall length. For reference, the magazine’s size was increased by less than 20% while its capacity was increased by around 35%. From a number’s perspective, I’d call that a win.

The benefits of magazine extensions aren’t isolated to pistol magazines. A rifle shooter will enjoy similar benefits with extensions on their rifle magazines much the same as shooters using pistol magazines with extensions. I recently reviewed the Lancer plus six extension in conjunction with their L5 Warfighter magazine and have since included those magazines in my rifle loadout. By using magazine extensions, I experienced the benefit of adding ammunition (12 additional rounds over two magazines) to my loadout without re-arranging equipment or removing gear to have enough real estate to add an additional magazine.

Lancer L5 magazines with plus 6 extensions on a rifle plate carrier. Note: the magazines sit slightly higher due to the plus six extensions. The tension on the magazine carriers was adjusted due to the increased weight on top.

Things to Know for Installing and Using Magazine Extensions

A common question about magazine extensions is how they’re installed. The process is relatively the same regardless of the magazine manufacturer. The base plate is removed by pressing on the pin (attached to the magazine insert) or slot in the base plate. This is normally a small hole or slot in the middle of the base plate with a pin or other shape filling the void. The base plate is then slid off and removed (Glock magazines require some effort due to the slots on either side of the magazine body holding the floorplate in place).

Several magazines from Glock (ETS Glock mag on far left), HK, and Sig. Nearly every modern double-stack pistol magazine has a detent pin or slot that holds the base plate in place. Just be slow and careful when removing the base plate. Springs come out fast!

When doing so, be careful as the removal of the base plate can allow the magazine spring to shoot out the bottom. Partially sliding off the floorplate and then using a finger to hold onto the compressed magazine spring helps prevent the spring from shooting out. Some magazine extensions include a new spring, others do not. If no spring is provided, continue to use the factory one and install the new extended base plate as directed by the manufacturer. Most extended base plates are held in by a retention screw to prevent the magazine from sliding off the extension. I strongly encourage using Loctite on this screw (use blue, NOT RED, Loctite so it can be removed for maintenance) to prevent it from coming loose. If in doubt about installation, consult the magazine extension manufacturer about what their recommendations are for installation.

Magazine set screw for the Lancer L5 (left) and TTI Glock (right) plus 6 extensions. The Lancer set screw is just a single screw while the TTI has a set screw that holds a pin in place. Check these regularly when handling your magazines to ensure they haven’t moved.

As in most things, magazine extensions are not a free lunch when enjoying the benefits discussed above. Magazine extensions increase the weight of the magazine and change its balance. When carried in some magazine carriers, the extensions can cause the magazine to sag away from the body. Due to the extended base, magazine extensions can pop off the magazine body if they are torqued in opposite directions from being struck against an object or dropped with significant force and/or caught on an obstacle.

The best antidote for addressing these concerns and considerations is to train with these extensions after installing them and put several magazines of ammunition through each one on the range. See how they affect your equipment setup and test them through day-to-day actions like sitting, riding in a car, standing, running, etc. Inspect the magazines regularly as part of your firearm maintenance routine to verify there are no defects or developing failures with the magazine body and extension.

As an advocate for maximizing your survivability and performance through quality training and equipment, you and your equipment are only as good as what you have put them through. Everything else beyond that is theoretical in terms of what the standard of performance will be. With proper maintenance and practice, magazine extensions offer a compact advantage to add more ammunition to your loadout professionally, personally, or recreationally.

Tom Stilson's firearms career began working at a gun store counter in 2012. He later conducted fine and collectible firearm appraisals before becoming the national firearms compliance merchant for a major outdoor retailer. In 2015, he entered public service with a career in law enforcement. Tom has a wide range of experience working for big, small, urban, and rural agencies. Among his qualifications, Tom is a certified firearms instructor, field trainer, and in special weapons and tactics. With years of experience in the field of geochemistry and a B.S. from Stanford University in Geological and Environmental Sciences, Tom takes a science-oriented approach to training, reviews, and firearms. If not on his backyard range, he spends his time with family or sharing his passion for firearms and law enforcement.

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